Cohen, K., Weizman, A., & Weinstein, A. (2019). Modulatory effects of cannabinoids on brain neurotransmission. European Journal of Neuroscience, 50(3), 2322-2345.
The authors have presented a comprehensive review of the effects of cannabis on the human brain. Specifically, Cohen et al. (2019) present current literature on the impacts of cannabinoids the neurotransmission on the brain. Evidence from human studies and pre-clinical studies have dominated their discussion. The basic idea presented is that cannabis psychoactive composites, which is also the case with marijuana-like drugs with synthetic cannabinoids. Clinical and pre-clinical data from the studies explored have focused majorly on cannabinoid type-1 and type receptors, which have been denoted as CB1 and BC2 respectively. Cohen et al. (2019) express that pre-clinical studies exploring the effects of cannabinoids on dopamine neurotransmission find that acute stimulation of CB1 tends to indirectly induce the mesolimbic dopaminergic activity. Additionally, there is an increased release of dopamine in the striatal regions. Human studies on the same subject reveal that Delta-9-tetrahydrocannabinol (Δ9-THC), which is the main substance in cannabis, tends to cause higher risks of psychotic disorders. Another aspect of mental health is receptor availability where the authors reveal that heavy use of the drug causes a decrease in the striatal dopamine receptor occupancy.
It can be seen that this review approaches the link between drug use and mental health from a physiological perspective where the physical and chemical properties of the drug users’ brains are explored. In addition to the neurotransmission and receptor availability, Cohen et al. (2019) discuss the availability of dopamine transporter (DAT) and serotonin neurotransmissions. However, the authors find that only a limited number of studies focus on the DAT, which means that the validity of the findings cannot be established. Regarding the serotonergic system, the authors find that serotonin (5-HT) plays a major role in mental functions, especially in regulating and controlling cognition, perception, anxiety, and mood. Therefore, evidence from pre-clinical studies indicates that the activation of CB1 receptors causes a decrease in the release of 5-HT. In human studies, the effects of cannabinoids on the 5-HT system have also been documented where such psychopathologies as anxiety, depression, Alzheimer’s disease, and schizophrenia have been linked with the consumption of cannabis. Similar effects are also observed in other brain functions, including glutamate neurotransmission, Gamma-Aminobutyric Acid (GABA), and the cholinergic system where both pre-clinical and human are explored. Overall, there are multiple themes explored in this review of how cannabinoids affect the human brain. The authors have been comprehensive, which means that the conclusion that cannabis consumption causes mental health issues is well-evidenced and justified. Additionally, they offer clinical implications for the data examined, including the fact that cannabinoids cause mental health issues. However, the authors also notice that most of the scholarly work referenced comprises of pre-clinical studies, either in vitro or in vivo. The main issue with such studies is that they tend to use multiple methods and tools, which means that they have high variability and inconsistencies in the results.
Lowe, D., Sasiadek, J., Coles, A., & George, T. (2019). Cannabis and mental illness: A review. European Archives of Psychiatry and Clinical Neuroscience, 269(1), 107-120.
The authors also present a review on the subject of cannabis use and its effect on mental illness. Lowe et al. (2019) express that the main concern is the fact that many western countries are on the course to legalize marijuana, which will adversely affect vulnerable populations. There is a need to understand the key consequences of the use of this drug before the masses can be allowed to use it. Some key statistics have been used to support the concerns regarding the legalization. For example, Lowe et al. (2019) establish that the consumption rates in Canada in 2017 had reached 43% for people between 16 and 24 years. Additionally, the rates for individuals above 25 years were estimated at 18%, which indicates a trend of rising cannabis use among young people. The major observation made by Lowe et al. (2019) is that such mental illnesses as moods, schizophrenia, and anxiety disorders are common among cannabis users. The review of the impacts of cannabis has been presented in terms of mental illnesses addressed as separate themes, and additional sections regarding the conceptualization of key constructs. First, the authors have explored the link between cannabis and schizophrenia where they find that the drug is a major cause of psychotic illness. Estimates indicate that one in four persons diagnosed with cannabis use disorder (CUD) will develop a psychotic illness. The key substance in cannabis associated with this mental issue is Tetrahydrocannabinol (THC), where half of the heavy cannabis users are likely to develop psychosis.
Second, major depressive disorder and bipolar disorder (MDD and BD respectively) are also shown to be key outcomes for marijuana consumption. The main source of evidence used by Lowe et al. (2019) is a 40-year research comprising a cohort of 400 people across diverse points in time. The key results indicated that the use of cannabis was correlated with high risks of MDD and BD. Other mental illnesses explored are anxiety disorders and posttraumatic stress disorders (PTSD), all of which have been positively associated with the consumption of cannabis. In addition to the mental illnesses, Lowe et al. (2019) also offered a critique of the methodologies used in the current literature on the subject. The first issue is that cannabis tends to cause more physical harms and long-term illnesses that should not be overlooked. Even though the focus was on mental illness, the scholars examine the contradictory constructs of the self-medication hypothesis and addiction vulnerability. The argument is that people use cannabis for self-medication, especially to cope with mental illnesses, despite research showing that CUD causes mental illnesses. Lastly, societal implications of the legalization of marijuana have been highlighted, especially THC’s impacts. Most importantly, issues of policymaking and public education were discussed. Essentially, these issues are the result of misperceptions of cannabis as ‘only good’ or ‘only bad’ where people fail to acknowledge both sides of the impacts. Additionally, the fact that cannabis is perceived as an alternative medicine is a major concern, which dictates that the public should be well-educated on the matters of using marijuana.
Wlodarczyk, O., Schwarze, M., Rumpf, H.-J., Metzner, F., & Pawils, S. (2017). Protective mental health factors in children of parents with alcohol and drug use disorders: A systematic review. PLoS One, 12(6), 1-15.
The scholars have presented a systematic review of mental health factors affecting children whose parents have drug and alcohol use disorders. A deviation from the above two articles has been made in the sense that the focus is not on the users themselves, but on the children. This deviation can be seen as an opportunity to explore the indirect links between drug use and mental health. Wlodarczyk et al. (2017) explain that drug-using parents expose their children to environments of severe stress, which potentially increases the risks of psychological and social problems. However, the scholars have indicated that there lacks epidemiological data in this regard, which means that only estimations are possible. As a systematic review, the scholars describe the materials and methods, including a search strategy in the form of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). The selected studies had to pass a quality evaluation using a mixed-methods Appraisal Tool (MMAT) checklist. Cross-sectional studies had to pass additional tests that classified them as low, medium, and high quality. Lastly, a narrative analysis was used as the method for the synthesis of the results.
The systematic review yielded 3,402 articles where 11 of them published between 2003 and 2013 met the criteria. From these articles, a total population of children affected by drug-using parents was 1,376 whose ages ranged between 1 and 20 years. Wlodarczyk et al. (2017) noticed a consistency in the findings establishing that mental health of children was affected by the parent-child attachment where the parents abused drugs. The results discussed included the outcomes of the selection of the materials and the major observation However, the main focus should be on the links between drug use and mental health for children with drug-abusing parents. In this regard, Wlodarczyk et al. (2017) confirmed their hypothesis that the home environment in which children are brought up affects their mental wellbeing. The key construct in this discussion is the parent-child attachment and how it is affected by drug use. In many cases, children have been found to develop coping mechanisms to deal with any implications. Even with drug-abusing parents, the parent-child attachment was observed to be persistent unless the children displayed such behavioral characteristics as highly impulsive personality.